if you wanted to follow jesus, you had to become a jew and obey jewish law. and peter wielded considerable power back in jerusalem, power given to him by jesus. >> according to the gospel of matthew, jesus says to peter, "you are peter," the greek term for rock, petros, "and on this rock, petra, i will build my church." >> peter became the head of the small christian church that was centered in jerusalem itself. so early on, peter was the key player in early christianity, and according to our traditions, was the one who converted jews early on to believe in jesus as the messiah. >> but there was another crucial leader of the early followers of jesus. his name was james, and he seemed to have the ultimate trump card in the new faith. >> because he was jesus' earthly brother, he was naturally raised in prominence among the christians of jerusalem, and eventually then, it wasn't long before he became the leader of the jerusalem church. >> when james agreed with peter, jesus was for the jews. within two decades of the crucifixion of jesus, scholars say, christian